Next generation mobile systems and services typically referred to as Third Generation or 3G systems and services, are now coming on-line. 3G mobile technology provides better quality voice, Internet, and related multimedia services. The International Telecommunication Union (ITU) has worked with industry bodies to define and approve technical requirements, standards, and spectrum allocation for 3G systems under the IMT-2000 (International Telecommunication Union-2000) and related programs.
CDMA2000 is a 3G system which has evolved from existing wireless standards, for example, IS-95, and which allows wireless operators to provide enhanced service in an environment characterized by new market dynamics associated with increased mobility, mobility enhancing equipment, and wireless access to the Internet. CDMA2000 specifies both an air interface and a core network technology for delivering improved levels of service demanded by increasingly mobile customers.
It will be appreciated that in accordance with various common communication architectures, CMDA2000 systems include layers within, for example, the seven layer protocol stack commonly understood by those of ordinary skill in the art as the Open Systems Interconnect (OSI) model. One such layer of the OSI stack architecture present within CMDA2000 systems is the Physical Layer where in an exemplary receiver, signals are received, despread, demodulated, decoded, channelized, framed and the like. As information is decoded and channelized, frames are constructed or re-constructed in accordance with relevant standards. Remaining layers in ascending order within the typical layered architecture include MAC Layer, Security Layer, Connection Layer, Session Layer, Stream Layer, and Application Layer. An exemplary CDMA2000 system may further operate in both single carrier and multiple carrier environments and according to both Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD).
Physical layer channels are implementation independent and may be prefixed with an “R” standing for an uplink or Reverse link channel portion extending from a Mobile Station (MS) to a Base Station within a RAN, while “F” denotes a downlink or Forward link channel portion extending from the Base Station to the MS. For simplicity, prefixes will not be used herein and instead reference is made to channels by name only. It should further be noted that reference to a channel generally refers to the combination of a forward and a reverse portion thereof, although generally only one channel portion such as a forward portion or a reverse portion is discussed at one time.
Physical channels may be classified as dedicated and common channels. For example, a Dedicated Physical Channel (DPCH) offers a point-to-point connection while a Common Physical Channel (CPCH) offers a point-to-multipoint access. Within a typical CDMA2000 system, many channel types are available and have been listed and described briefly hereinafter. A typical CDMA2000 system provides a Dedicated Physical Channel (DHCH); a Fundamental Channel (FCH) for transporting dedicated data; a Supplemental Channel (SCH) for meeting required data rates through dynamic allocation; a Dedicated Control Channel (DCCH) for transporting mobile-specific control information; and a Dedicated Auxiliary Pilot Channel (DAPICH) optionally used with antenna beam-forming and beam-steering techniques to increase the coverage or data rate towards a particular user. As previously noted, the above described channels are available on both the forward and reverse channels. Additional channels are specific to forward or reverse channels as noted hereinafter. A Pilot Channel (R-PICH) provides capabilities associated with coherent detection; a Forward Pilot Channel (F-PICH) provides soft handoff and coherent detection capabilities; a Forward Common Auxiliary Pilot Channel (F-CAPICH) provides soft handoff and coherent detection capabilities; a Forward Paging Channel (F-PCH) provides paging functions using short burst data communications; a Forward Common Control Channel (F-CCCH) provides paging functions supporting different data rates and a capability for short burst data communications; a Forward Sync Channel (F-SYNC) provides an MS with system information and synchronization; a Reverse Access Channel (R-ACH) provides a multiple access channel where a MS can communicate messages to the base station; and a Reverse Common Control Channel (R-CCCH) which is similar to the R-ACH but is configured to transport control information.
Two channels of interest in a typical communication between a MS and a base station or other station or node within a RAN, include the SCH and the FCH/DCCH. As noted above, the FCH may be used for transporting dedicated data and the DCCH is used for transporting mobile-specific control information. Both the FCH and DCCH are characterized as high-reliability low data rate channels, while the SCH is used for meeting required data rates through dynamic allocation and is characterized as a low reliability high data rate channel. By reliability, reference is made to the degree of signaling accuracy associated with each channel. SCH channels by design are geared toward carrying large volumes of traffic with less concern for accuracy.
Problems arise however in that frame classifications, such as whether a transmission is present, e.g. a continuous/discontinuous transmission (TX/DTX) classification and Rate determination algorithms operate independently on each channel. Further, TX/DTX classifications are used for power control and Radio Link Protocol (RLP) purposes, thus accurate classification has significant ramifications throughout the RAN. Since the SCH is a low reliability channel, capacity may be sacrificed when rate determinations made for the SCH channel are erroneous. Typically, since the SCH channel is used for high capacity high data rate data transfers associated with traffic which may have data components being transferred on other channels, errors in the rate determination for the SCH channel, or any channel, may reduce throughput, power efficiency, bandwidth utilization, and the like, and thus may have an overall negative impact throughout the system. For example, power increases resulting from improper channel classifications can result in increases in co-channel interference. Conversely, data loss which can also be associated with improper classification can disrupt protocol operation, error correction, data recovery and the like. It would be desirable therefore to increase the accuracy of frame classifications so that overall RAN performance can be improved.